1. Field of the Invention
This invention relates to gas generators or inflators that utilize the combustion of a solid fuel gas generant composition for the generation of a gas for rapidly inflating vehicle passive restraint inflatable crash protection bags, and more particularly, to an improved housing construction for such inflators.
2. Description of the Prior Art
Many forms of gas generators or inflators that utilize combustible solid fuel gas generant compositions for the inflation of inflatable crash protection or "air" bag restraint systems are known in the prior art. One form of such gas generators includes as its main component parts an annular reaction or combustion chamber which is bounded by an outer casing or housing structure, as disclosed in U.S. Pat. No. 4,296,084, granted to G. V. Adams and F. E. Schneiter and assigned to the assignee of the present invention. The combustion chamber encloses a rupturable container or cartridge that is hermetically sealed and contains therein solid gas generant material in pelletized form, surrounded by an annular filter. The generator further includes a central ignition or initiator tube, and a toroidal filter chamber adjoining and encircling the combustion chamber with an inner casing or housing structure in close surrounding and supporting relationship to the rupturable container, the inner casing being formed by a cylinder having uniformly spaced peripheral ports or orifices near one end. These orifices provide exit holes for the flow of inflation gas from the combustion chamber.
Gas generators or inflators must withstand enormous thermal and mechanical stresses for a short period during the gas generation process. Thus, inflators that have been and are currently being used to fill automobile or other vehicle crash bags are fabricated using steel for the casing and other housing structural components, with the structural components being joined together by screw threads, roll crimping or welding.
Recent emphasis on weight reduction in automobiles has created a need, and a demand, for a lighter weight crash bag inflation system. This is of particular importance in a system for driver crash protection where the inflator is mounted on the steering wheel since the availability of a lighter weight inflator enables a reduction to be made in the weight of the steering wheel and steering column on which the inflator is mounted. It has been determined that the most significant weight reductions in the inflator can be achieved by the substitution of aluminum for the steel housing and other structural components, aluminum already being used internally in the inflator as containers, seals and filter media.